Propagation in radially-inhomogeneous single-mode fibre

The propagation of electromagnetic waves along a radially-inhomogeneous single-mode optical fibre with small index difference between core and cladding is studied. As in the case of the step-index fibre the propagation modes are weakly guided and their transverse fields are essentially polarized in one direction. The simple field descriptions and characteristic equation obtained here enable mode spot size and bending loss to be determined and are useful for practical design work of radially-inhomogeneous single-mode optical fibres